Mechanism for producing step by step motion



March 9, 1943. 'F. R. FORD 2,313,633

MECHANISM FOR PRODUCING STEP BY STEP MOTION Filed Dec. 11, 1941 3 Sheets-Sheet l INVENI' E F'kqn RD HAIQI Ford S CWIMML March 9, 1943.

F. FORD Filed Dec. 11, 1941 5 Sheets$heet 2 @w 3 w N IQ- T 0 m. m m. A W l M m m VA m E v mm Q 09 N9 BM R 3 ,4 W qnz HI ll B 6r @0- 0M 5- 3 o. E mg I. .1 W m0. m: E 7 mo MNSQM March 9, 1943. F. R. FORD 2,313,533 MECHANISM FOR PRODUCING S TEP BY STEP MOTION Filed Dec. 11, 1941 3 Sheets-Sheet 3 mvem-ow- Frank R YKHd Ford m mt; ATTY.

Patented Mar. 9, 1943 MECHANISM FOR PRODUCING STEP BY STEP MOTION Frank Ronald Ford, Sparkbrook, Birmingham, England Application December 11, 1941, Serial No. 422,500 In Great Britain-July '23, 1941 5 Claims. (01. 101-1325) This invention relates-to mechanism for producing step by step motion and has for its object to provide means whereby a member mounted for reciprocating movement can be moved one step at a time in either direction at will. Further in the preferred form the mechanism enables the member to be moved by hand any number of steps at one movement in either direction.

The mechanism constructed in accordance with the present invention comprises a pair of rack bars mounted for limited reciprocating movement upon a pair of fixed pins; each bar having a pair of primary cam slots, each pin engaging two of the primary slots one in each bar, these primary slots being arranged with their cam portions normally adjacent the pins and at opposite ends, a pin on each bar engaging a secondary cam surface on the other bar, an

abutment on the member to be moved for each rack bar, means acting on the rack bars tending to pull the cam portions of the primary slots into engagement with the fixed pins, whereby the teeth of the rack bars are normally out of engagement with the abutment, but endwise movement applied to either rack bar brings one of its teeth into engagement with one of the abutments and so produces movement of the member to be moved and also brings the tooth on the other rack bar into position in which it acts as a stop to limit the said movement.

The teeth on the two rack bars may be of ratchet form and arranged in opposite directions.

The abutments are of ratchet form and they may consist of pivoted detents acted upon by springs pressing them up against stops so that they act as immovable stops against pressure in one direction but can give way to pressure in the opposite direction.

If it is desired that it should be possible to move the member to be moved in either direction by a greater number of steps than one at a single movement the member to be moved may be provided with a spring pressed nose adapted to engage in succession a number of recesses or shoulders in a bar placed parallel to the movement. The two rack bars forming the step by step motion are normally out of engagement with the abutments on the member to be moved so that movement over and above one step is thus freely permitted.

The present invention is particularly applicable to office appliance machines such as duplicators, typewriters, etc. In the accompanying drawings it is shown applied to the feed tray of a duplicating machine constructed in accordance with my U. S. A. application Serial No. 372,119.

Referring to the drawings:

Figure 1 is a plan view showing one form of the invention.

Figure 2 is a section on line 22 of Figure 1.

Figure 3 'is a detailed view showing the step by step motion.

Figure 4 is a perspective view showing the parts of the step by step motion separated.

The machine illustrated in the drawings apart from the mechanism controlling the movements of the tray forms the subject of an application filed concurrently herewith. The machine is a duplicating machine and comprises a cylinder I5 on which a master sheet is fastened, a pair of pressure rollers 39 which are adapted to press the copy sheets 55 on to the master sheet on the cylinder. The machine also comprises moistening members 55 by which the copy sheets are moistened before reaching the master sheet.

The tray to which the step by step motion according to the present invention is applied is shown at 28. This tray is supported upon a pair of bars 21 and on its underside it is provided with a block I00 containing a nose shaped pin IBI pressed by a spring I02 behind which is a screw I03. The nose shaped pin Iill projects into the circular hole IM which extends through the block.

The machine is provided with a moving carriage indicated generally in Figure 1 at I05 and this carriage carries a bar I06 in which is a helical groove IN. This bar IIlB extends through the opening I04 and as the feed tray 28 moves sideways the nose shaped pin IOI engages successive turns of the slot I 01 thus forming a check to the movement.

The arrangement further provides that the feed tray 28 can be pushed sideways in either direction for any number of spaces that may be required and in order to facilitate this movement it is provided with handles I08.

The step by step mechanism is shown in detail in Figures 3 and 4. Brackets Hi9 forming part of the carriage I05 are provided with fixed pro- J'ecting pins no and mounted for reciprocating movement on these pins are two rack bars III and I I2. These rack bars are provided with teeth H3 and H4 of ratchet form and arranged in opposite directions.

The rack bar II I is provided with two primary cam slots I I5 each having its left hand end II 6 inclined downwardly.

The rack bar H2 is also provided with two cam slots I I! each having its right hand end I I8 inclined downwardly.

These rack bars III and H2 are mounted on the pins IIU as shown in Figure 3 with the inclined or cam portions of the slots engaging the pms.

Further the bar III is acted upon by a spring I I 9 tending to pull it to the right and the bar I I2 is acted upon by a spring I20 tending to pull it to the left.

The upper edge of the rack bar I I I is provided with a secondary cam surface I2I engaged by a pin I22 projecting from the back of the rack bar The top edge of the rack bar H2 is provided with a secondary cam surface I23 which is engaged by a pin I24 projecting from the front of the rack bar I I I.

On its upper side the feed tray is provided with a bracket I25 having a web I26 on opposite sides of which are pivoted two ratchet like detents I21 and I28. These are oppositely arranged and are pivoted respectively at I29, I30. Each is acted upon by a spring I3I the detent I21 being pushed by the spring against a stop I32 and the detent I28 being pushed by the spring against. a stop I33.

The teeth II4 are adapted to engage the detent I21 and the teeth I I3 are adapted to engage with the detent I28.

As will be seen from Figure 3, however, the teeth of both rack bars are normally out of engagement with the detents so that the tray can be pushed from side to side by any required distance or any number of steps, the nose shaped pin IDI moving over successive turns of the helical groove IO'I.

When it is desired to move the tray in either direction with a step by step movement one ofthe rack bars I I I or I I2 is operated.

When the rack bar III is pushed to the left the engagement of its primary cam slots by the pins III! causes it to move downwardly as Well as moving to the left and brings one of its teeth into engagement with the detent I28. At the same time the pin I24 acts upon the secondary cam surface I23 of the rack bar H2 and forces that rack bar downwardly and a little to the right as it is constrained to do by the engagement between these primary cam slots and the pins I Hi. This brings one of the teeth II4 into a position to engage the detent I21 and to act as a stop to limit the length of the step of movement.

:When the rack bar III is released both rack bars return to their original position.

.The movement is exactly the same only reversed if the rack bar I I2 is pushed to the right.

Both rack bars are provided with finger pieces I 34 by which they may be operated.

What I claim then is:

1. Step by step motion mechanism comprising a pair of rack bars, each bar having a pair of primary cam slots, a pair of fixed pins, each engaging two primary cam slots one in each rack bar, said slots being arranged with their cam portions normally engaged by the pins and at opposite ends of the slots, each bar being formed with a secondary cam surface, a pin on each rack bar and projecting laterally therefrom and engaging the secondary cam surface of the other rack bar, a member to which the step by step motion is to be imparted by the teeth of the rack bars, abutments on said member for engagement one by the teeth of each rack bar, and means acting on the .rack bars tending to pull the cam portions of the primary cam slots into engagement with the fixed pins, whereby the teeth of the rack bars are normally out of engagement with the abutments, but endwise movement applied to either rack bar brings one of its teeth into engagement with the abutment and so produces a movement of the member to be moved, and also brings a toothof the other rack bar into a position in which it cooperates with the abutment to limit such movement.

2. Mechanism according to claim 1, wherein the teeth on the rack bars are of ratchet form and arranged in opposite directions.

3. Mechanism according to claim 1, wherein the abutments on the member to be moved are of ratchet form, and are pivotally mounted, a spring acting on each of said abutments, and a stop on the member to be moved for each abutment, each spring pressing its abutment against the stop.

4. Mechanism according to claim 1 including a fixed bar having a series of recesses and a spring pressed nose on the member to be moved engaging one of said recesses.

5. Mechanism according to claim 1, wherein the member to be moved is the feed tray of a duplicating machine having a laterally moving carriage and the ratchet bars and fixed pins are mounted on the carriage of the machine.

FRANK RONALD FORD. 

